In recent years, high-luminance light-emitting diodes (LEDs), which exhibit high light intensity and are great in heat generation, have been commercialized and have been in wide use for general illumination. This entails a change from existing nylon-based reflectors to silicone or epoxy resin package materials, for which novel characteristics are required for inner resins. In JP-A 2005-272697 as Patent Document 1, it is stated that a phenolic antioxidant and a hindered amine light degradation inhibitor are added to phenol-based silicone resins thereby providing a sealing material that is excellent in heat resistance, light resistance and weatherability. However, this silicon resin composition is lowered in the effect of the light degradation inhibitor after its long use, with some concern that the resin undergoes discoloration due to the light degradation of the phenyl group and also suffers degradation owing to the breakage of siloxane bonds.
JP-T 2009-527622 as Patent Document 2 describes a silicone resin composition comprising a phenyl group-containing organopolysiloxane and a hydrogendiorganosiloxy-terminated oligodiphenylsiloxane as being useful for prolonging the life of LED. However, when such a silicone resin composition is employed for the package of high-luminance LEDs which are high in light intensity and great in heat generation, cracks are apt to occur at LED package ends or the base of a lead frame. Especially, because of poor adhesion to silver, peeling is liable to occur at the interface between the LED package and a silver frame.